深入理解Java显式锁的相关知识

lock.lock();
try {
    // 业务逻辑
} finally {
    lock.unlock();
}

public class ReentrantLockTest {

    private Lock lock = new ReentrantLock();
    private int count = 0;

    public int getCount() {
        return count;
    }

    private static class ReentrantLockThread extends Thread {
        private ReentrantLockTest reentrantLockTest;

        public ReentrantLockThread(ReentrantLockTest reentrantLockTest) {
            this.reentrantLockTest = reentrantLockTest;
        }

        @Override
        public void run() {
            for (int i = 0; i < 100000; i++) {
                reentrantLockTest.incr();
            }
            System.out.println(Thread.currentThread().getName() + " end, count =  " + reentrantLockTest.getCount());
        }
    }

    private void incr() {
        lock.lock();
        try {
            count++;
        } finally {
            lock.unlock();
        }
    }

    private void decr() {
        lock.lock();
        try {
            count--;
        } finally {
            lock.unlock();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        ReentrantLockTest reentrantLockTest = new ReentrantLockTest();
        new ReentrantLockThread(reentrantLockTest).start();

        for (int i = 0; i < 100000; i++) {
            // 递减100000
            reentrantLockTest.decr();
        }
        System.out.println(Thread.currentThread().getName() + " count =  " + reentrantLockTest.getCount());
    }
}

private final ReadWriteLock lock = new ReentrantReadWriteLock();
private final Lock getLock = lock.readLock(); // 读锁
private final Lock setLock = lock.writeLock(); // 写锁

public class ConditionTest {

    private volatile boolean flag = false;
    private Lock lock = new ReentrantLock();
    private Condition condition = lock.newCondition();

    private void task1() {
        lock.lock();
        try {
            try {
                System.out.println(Thread.currentThread().getName() + " 等待中");
                condition.await();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName() + " 等待结束");
            System.out.println("发送邮件");
        } finally {
            lock.unlock();
        }
    }

    private void task2() {
        lock.lock();
        try {
            try {
                System.out.println(Thread.currentThread().getName() + " 等待中");
                condition.await();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName() + " 等待结束");
            System.out.println("发送短信");
        } finally {
            lock.unlock();
        }
    }

    private void updateFlag() {
        lock.lock();
        try {
            this.flag = true;
            this.condition.signalAll();
        }finally {
            lock.unlock();
        }
    }

    private static class ConditionThread1 extends Thread {
        private ConditionTest conditionTest;
        public ConditionThread1(ConditionTest conditionTest) {
            this.conditionTest = conditionTest;
        }

        @Override
        public void run() {
            if (!conditionTest.flag) {
                conditionTest.task1();
            }
        }
    }

    private static class ConditionThread2 extends Thread {
        private ConditionTest conditionTest;
        public ConditionThread2(ConditionTest conditionTest) {
            this.conditionTest = conditionTest;
        }

        @Override
        public void run() {
            if (!conditionTest.flag) {
                conditionTest.task2();
            }
        }
    }

    public static void main(String[] args) throws InterruptedException {
        ConditionTest conditionTest = new ConditionTest();
        new ConditionThread1(conditionTest).start();
        new ConditionThread2(conditionTest).start();
        Thread.sleep(1000);
        System.out.println("flag 改变。。。");
        conditionTest.updateFlag();
    }
}